WO2008059888A1

WO2008059888A1 - Purifying apparatus, purifying method, exhaust gas purifying system, and method for producing purifying structure

Info

Publication number: WO2008059888A1
Application number: PCT/JP2007/072114
Authority: WO
Inventors: Yoshinobu Yoshihara; Yasufumi Nakanishi
Original assignee: The Ritsumeikan Trust
Priority date: 2006-11-14
Filing date: 2007-11-14
Publication date: 2008-05-22
Also published as: JP2008119618A

Abstract

Disclosed is a purifying apparatus comprising a purifying structure (30) having an ion-conductive solid electrolyte (1), and a first electrode (3) and a second electrode (4) respectively formed on one side and the other side of the solid electrolyte (1). The purifying structure (30) is porous and collects unburned particles at the first electrode (3) side by passing an exhaust gas containing the unburned particles from the first electrode (3) side to the second electrode (4) side. The first electrode (3) side serves as an oxidizing unit for oxidizing the collected particles with oxygen ions which are supplied to the first electrode (3) side by the solid electrolyte (1). The purifying structure (30) further comprises a support (40) for increasing the mechanical strength.

Description

Specification

Purification device, purification method, exhaust gas purification system, and purification structure manufacturing method

Technical field

The present invention relates to a purification device, a purification method for purifying unburned particulates (diesel particulates) and nitrogen oxides discharged from a combustor, and an exhaust gas for purifying exhaust gas containing diesel particulates and nitrogen oxides. The present invention relates to a purification system and a method for manufacturing a purification structure. Background art

[0002] Currently, the main role of logistics that supports people's lives and corporate activities is transportation by truck, which is indispensable for economic activities. The diesel engine that powers the truck is effective for energy conservation and global warming, which has higher thermal efficiency than other heat engines. However, diesel engines emit large amounts of air pollutants such as nitrogen oxides (NOx) and particulate matter (PM). For this reason, trucks have a considerable impact on environmental issues. Therefore, there is a need for efforts to disseminate diesel engines with low environmental impact and peripheral equipment, maintain economic activities, and further develop them.

[0003] Currently, there are a PM purification method using a filter and a NOx purification method using a catalyst, which are known as purification methods for purifying NOx and PM discharged from a diesel engine. In addition, as described in JP-A-9-299748, as an exhaust gas purification system using a solid electrolyte, electrodes including a catalyst are laminated on both sides of the solid electrolyte, and the solid electrolyte side of the power sword There is a method that makes it possible to decompose and remove nitrogen oxides by supplying combustion gas containing nitrogen oxides to forcibly removing active oxygen generated during the decomposition process of nitrogen oxides through a solid electrolyte. However, this does not purify PM.

[0004] The conventional PM purification method has a problem of how to remove and regenerate the fine particles accumulated on the filter. A continuous regeneration trap, one of the continuous regeneration systems, oxidizes NO in the exhaust gas to NO, and particulates collected on the filter are oxidized by this NO. There is S power to make it. However, if the exhaust gas temperature does not reach 250 ° C, particulate oxidation will not occur and a separate NO purification device will be required. DPNR (Diesel Particulate-NOx Reduction system) is a porous ceramic filter that supports NOx storage reduction catalyst. There is a method in which PM is oxidized by oxygen radicals generated during NOx occlusion, and the fuel injection amount is increased periodically and instantaneously, and NOx adsorbed by CO and HC emitted at that time is reduced. However, this method requires delicate and accurate fuel injection control, and has problems such as deterioration of durability, high cost, and deterioration of fuel consumption. For this reason, conventionally known purification methods are not sufficient.

Disclosure of the invention

[0005] The present invention provides a purification device, a purification method, and an exhaust gas purification system that are capable of purifying exhaust gas and efficiently purify, and are further used in the purification device and the exhaust gas purification system. An object of the present invention is to provide a method for producing a purification structure.

[0006] In order to achieve the above object, a purification apparatus of the present invention includes a solid electrolyte having ionic conductivity and capable of supplying oxygen ions to one side, and one side and the other side of the solid electrolyte. Provided with a purification structure having a first electrode and a second electrode provided, and the purification structure emits exhaust gas containing unburned fine particles discharged from the combustor force from the first electrode side to the second electrode. The fine particles can be collected on the first electrode side by passing to the side, and the first electrode side is configured to collect the collected fine particles to the first electrode side by the solid electrolyte. It is an oxidation part that is oxidized by given oxygen ions, and the purification structure further includes a support for increasing the mechanical strength of the purification structure.

[0007] According to this configuration, since the purification structure is porous, it is possible to collect the fine particles on the first electrode side by passing exhaust gas containing unburned fine particles through the purification structure. Yes (can be filtered). Then, on the first electrode side, the solid carbonaceous fine particles in the collected fine particles can be oxidized with oxygen ions given by the solid electrolyte to form a carbon oxide.

Moreover, since the mechanical strength of the purification structure can be increased by the support, the purification structure It is possible to reduce the thickness of electrodes and solid electrolytes, which are other members constituting the body. That is, it is not necessary to increase the thickness of the electrode or the solid electrolyte in order to increase the mechanical strength of the purification structure. For this reason, it is possible to reduce the resistance when the exhaust gas permeates through the electrode and the solid electrolyte, and since the solid electrolyte is thinned, oxygen ions can be conducted with a small amount of applied voltage. Unburned particulates discharged include, for example, diesel engines, gasoline engines (direct injection gasoline engines), boilers, and industrial furnace power.

[0008] Further, the support is provided in a state of being laminated with the first electrode or the second electrode, and the support has a network structure or a porous structure through which the exhaust gas can pass. It is preferable.

Thereby, a support body can be included in the purification structure as an integral body, and the mechanical strength of the purification structure is increased. Further, since the support has a net structure or a porous structure, it is possible to transmit the exhaust gas. For this reason, the presence of the support does not prevent simultaneous purification of the solid carbonaceous fine particles and the nitrogen oxides in the exhaust gas.

[0009] In the purification device, it is preferable that at least one of the first electrode and the second electrode includes the same material as the solid electrolyte. According to this, since the decomposition reaction occurs at the interface between the electrode and the solid electrolyte, the reaction active point can be increased by mixing the solid electrolyte material with the electrode material. This can promote the decomposition of the components in the exhaust gas.

[0010] Furthermore, it is preferable that the first electrode contains silver. According to this, silver has the ability to adsorb oxygen. For this reason, there are many active sites that oxidize (decompose) the solid carbonaceous fine particles in the first electrode. Thereby, oxygen ions can be efficiently used for the oxidation of the solid carbonaceous fine particles, and a high decomposition rate can be obtained.

[0011] Further, the purification method of the present invention is provided with a porous solid electrolyte having ionic conductivity and capable of supplying oxygen ions to one side, and one side and the other side of the solid electrolyte. A purification method using a purification structure having a first electrode and a second electrode, and a support for increasing mechanical strength, from the one surface side of the porous solid electrolyte By passing the exhaust gas containing unburned particulates to the other side, the particulates The fine particles collected on the side are oxidized by the oxygen ions given to the one surface side by the solid electrolyte.

[0012] According to this method, the exhaust gas containing the unburned fine particles is passed through the porous solid electrolyte, whereby the fine particles can be collected on the one surface side. In addition, the solid carbonaceous fine particles in the collected fine particles can be oxidized on one side to form carbon oxides.

Further, since the mechanical strength of the purification structure can be increased by the support, it is possible to reduce the thickness of electrodes and solid electrolytes that are other members constituting the purification structure. That is, it is not necessary to increase the thickness of the electrode or the solid electrolyte in order to increase the mechanical strength of the purification structure. For this reason, it is possible to reduce the resistance when the exhaust gas permeates the electrode and the solid electrolyte, and since the solid electrolyte is made thin, oxygen ions can be conducted with a small amount of applied voltage.

[0013] Further, the exhaust gas purification system of the present invention is provided in an exhaust passage through which exhaust gas containing unburned particulates and nitrogen oxides discharged from the combustor passes, and in a part of the exhaust passage. An exhaust gas purification system comprising: a solid electrolyte having ionic conductivity and capable of supplying oxygen ions to one side; and one side of the solid electrolyte. A purification structure having a first electrode and a second electrode respectively provided on the side and the other surface side. The purification structure allows the exhaust gas from the exhaust passage to be discharged from the first electrode side. The fine particles can be collected on the first electrode side by passing to the second electrode side, and the first electrode side uses the solid electrolyte to collect the collected fine particles. Oxygen ions given to the electrode side And the second electrode side is a reducing unit that reduces nitrogen oxides contained in the exhaust gas that has permeated the purification structure, and the purification structure includes the purification structure. It further has a support for increasing the mechanical strength of the body.

[0014] According to this configuration, it is possible to simultaneously purify both the unburned fine particles and the nitrogen oxides contained in the exhaust gas flowing through the exhaust passage on one side and the other side of the purification structure. S can. These can be reduced. The exhaust gas flowing into the exhaust gas purification device is passed through a porous purification structure to remove unburned particulates. It can be collected automatically on the first electrode side of the body. That is, unburned particulates can be collected by filtering the flowing exhaust gas in the purification structure. This eliminates the need for a separate energy source for collecting particulates. Then, on the first electrode side of the purification structure, the solid carbonaceous fine particles contained in the collected unburned fine particles can be oxidized to carbon dioxide. Furthermore, on the second electrode side, nitrogen oxides contained in the exhaust gas that has permeated through the purification structure can be reduced to nitrogen gas.

[0015] The purification structure manufacturing method of the present invention is provided with a solid electrolyte having ionic conductivity and capable of supplying oxygen ions to one side, and one side and the other side of the solid electrolyte. A purification structure having a first electrode, a second electrode, and a porous support for increasing mechanical strength, wherein one surface side of the support is coated with an electrolyte slurry, Is fired to obtain a solid electrolyte on the support, and the electrode slurry is infiltrated from the other side of the porous support to the back of the solid electrolyte, and the electrode slurry is applied to the surface of the solid electrolyte. And is fired to obtain electrodes on both sides of the solid electrolyte.

According to this, since the electrode is fired after firing the solid electrolyte first, it is effective when the melting point of the electrode material is lower than the firing temperature of the solid electrolyte. That is, if the solid electrolyte and the electrode are simultaneously fired at a high temperature for firing the solid electrolyte, there is a possibility that the metal constituting the electrode may be aggregated. This manufacturing method can prevent this.

Brief Description of Drawings

FIG. 1 is a model diagram showing an embodiment of a purification device.

FIG. 2 is a model diagram showing another purification device. FIG. 3 is a model diagram showing still another purification device.

FIG. 4 is a model diagram for explaining the action of switching means for reversing the polarity of the applied voltage of the applying means.

FIG. 5 is a schematic diagram showing an outline of an exhaust gas purification system.

[Fig. 6] Fig. 6 is a configuration diagram of a main part of an exhaust gas purification device.

[Fig. 7] Fig. 7 is a main part configuration diagram showing a modified example of the exhaust gas purification device.

FIG. 8 is a schematic diagram showing an outline of another exhaust gas purification system.

9 is a main part configuration diagram showing an exhaust gas purifying device included in the purification system of FIG.

FIG. 10 is a model diagram showing still another purification device.

FIG. 11 is an explanatory diagram for explaining the mechanism of reduction of nitrogen oxides.

FIG. 12 is an explanatory diagram for explaining another mechanism of reduction of nitrogen oxides.

FIG. 13 is a schematic diagram showing an outline of another exhaust gas purification system.

14 is a main part configuration diagram showing an exhaust gas purifying device included in the purification system of FIG.

FIG. 15 is a graph showing the relationship between the reduction rate of solid carbonaceous fine particles and the purification time.

FIG. 16 is a graph showing the relationship between the reduction rate of solid carbonaceous fine particles and the current flowing through the purification structure.

FIG. 17 is a graph showing the relationship between the reduction rate of nitrogen oxides and the current flowing through the purification structure.

FIG. 18 is an explanatory view of a purification structure provided with a support.

FIG. 19 is an explanatory view for explaining a method for producing a purification structure provided with a support.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a model diagram showing an embodiment of a purification device. This purification device is for purifying diesel particulates contained in, for example, exhaust gas. This purification device can purify solid carbonaceous fine particles (particulate matter) PM in diesel fine particles. Specifically, this apparatus is an apparatus for purifying by oxidizing carbon contained in the solid carbonaceous fine particles M. In addition, the equipment can also process hydrocarbon particulates in the diesel particulates. The apparatus shown in FIG. 1 applies a voltage between the solid electrolyte 1 having oxygen ion conductivity and both sides of the solid electrolyte 1. Application means 2 is provided.

The solid electrolyte 1 shown in FIG. 1 has a panel shape, and the first electrode 3 is laminated on one surface 10 and the second electrode 4 is laminated on the other surface 11. As the solid electrolyte 1, for example, one used in a fuel cell can be applied, and an oxygen ion can be moved by applying a potential difference to both ends of the solid electrolyte 1. The first electrode 3 and the second electrode 4 are usually made of materials used as electrodes. The first electrode 3 and the second electrode 4 are plate-like, but the first electrode 3 and the second electrode 4 are porous electrodes so that the! /!

[0019] The application means 2 can be a DC power supply that is usually used, and preferably has a variable voltage. The application means 2 applies a voltage between both surfaces of the solid electrolyte 1 so that the first electrode 3 provided on one side 10 of the solid electrolyte 1 serves as a canon and the second electrode 4 provided on the other side 11 serves as a force sword. Apply. The voltage applied by the applying means 2 is set according to the electrical characteristics of the solid electrolyte 1 and the ambient temperature. For example, when the solid electrolyte 1 is yttrium-stabilized zirconium, it is 10 volts or less at an ambient temperature of 350 ° C.

[0020] This purification device is provided, for example, in an exhaust passage (not shown) for flowing exhaust gas discharged from a diesel engine. The one surface 10 side of the solid electrolyte 1 is provided so as to face the exhaust passage, and the one surface 10 side becomes the exhaust gas side G. The solid electrolyte 1 is provided so that the other surface 11 side of the solid electrolyte 1 faces the atmosphere side (atmosphere release side) A. A deposition surface 12 on which diesel particulates are deposited is formed on the surface 10 side, which is the anode side of the solid electrolyte 1, and the outer surface of the first electrode 3 is the deposition surface 12 in FIG. The outer surface of the first electrode 3 is the surface opposite to the contact surface with the solid electrolyte 1.

In the purification method using this purification device, diesel particulates are deposited on the deposition surface 12 on the one surface 10 side of the solid electrolyte 1, and a predetermined voltage is applied between both surfaces of the solid electrolyte 1 by the application means 2. Then, oxygen ions are supplied from the force sword side to the anode side. The oxygen ions oxidize diesel particulates present on the deposition surface 12 on the anode side. That is, oxygen contained in the atmosphere side A that is the force sword side is supplied as oxygen ions to the exhaust gas side G that is the anode side. As a result, the carbon contained in the solid carbonaceous fine particles M in the diesel particulates is continuously oxidized to carbon monoxide and carbon dioxide (C + O → C ○ ₂ , 2C + ○ ₂ → 2CO), and solid carbonaceous fine particles M are purified (decomposed). In FIG. 1, the arrows in solid electrolyte 1 indicate the direction of oxygen ion movement.

[0022] As described above, a voltage is applied between both surfaces of the solid electrolyte 1 having oxygen ion conductivity and the solid electrolyte 1 so that one side of the solid electrolyte 1 on which diesel particulates are deposited is the anode side. According to the purifying apparatus having the application means 2 to be applied, oxygen ions are supplied from the force sword side to the anode side through the solid electrolyte 1 by applying a voltage between both surfaces of the solid electrolyte 1 by the application means 2. The solid carbonaceous fine particles M in the diesel fine particles deposited on the anode side can be oxidized to form carbon oxides. For example, exhaust gas purification is performed by setting the surface of the solid electrolyte 1 on the power sword side to the atmosphere side (atmosphere release side) and the surface of the solid electrolyte 1 on the anode side to the exhaust gas side containing diesel particulates. Can do.

The purification device shown in FIG. 2 is obtained by omitting the first electrode 3 of the purification device of FIG. 1, and the other configurations are the same. That is, the electrode 4 on the force sword side is provided only on the other surface 11 side of the solid electrolyte 1. This purification device utilizes the fact that the solid carbonaceous fine particles M in the diesel fine particles have electrical conductivity. The surface 10 of the solid electrolyte 1 is directly used as the deposition surface 12 of the solid carbonaceous fine particles M contained in the diesel fine particles. When a certain amount of diesel particulate (solid carbonaceous particulate M) is deposited on one side 10 of the solid electrolyte 1 and energization is started by the application means 2, from the power sword side on the atmosphere side A to the anode side on the exhaust gas side G Oxygen ions are supplied.

That is, in this purification device, the lead wire 13 connected to the applying means 2 is connected to the one surface 10 side of the solid electrolyte 1. When diesel particulates are deposited on one side 10 of the solid electrolyte 1 and the solid carbonaceous particulates M in the deposited diesel particulates come into contact with the lead wires 13, application of voltage is started by the application means 2 and The carbonaceous fine particle M itself is used as an anode and energized. As a result, a predetermined potential difference is generated between both surfaces of the solid electrolyte 1 to supply oxygen ions. That is, when a certain amount of diesel particulates accumulates on the deposition surface 12, the purification is automatically started. The lead wire 13 is provided in a ring shape or a mesh shape on the one surface 10 side of the solid electrolyte 1. As a result, solid carbonaceous fine particles in diesel particulates partially deposited on one side 10 of the solid electrolyte 1 and on the side 12 of the deposit When the child M contacts the lead wire 13, it is purified.

[0025] In this manner, when the electrode on the force sword side is provided on the other surface side of the solid electrolyte 1, and diesel particulates are deposited on one surface side of the solid electrolyte 1, the diesel particulates are energized by the application means 2. The solid carbonaceous fine particles M in the diesel fine particles themselves constitute the anode. As a result, when a certain amount of diesel particulates accumulates on one side of the solid electrolyte 1, the solid carbonaceous particulates M in the diesel particulates are conductive, so energization is started and supply of oxygen ions from the force sword side begins. Is done. Thereby, purification of diesel particulates including solid carbonaceous particulates M on one side of the solid electrolyte 1 is automatically started. Therefore, no electrode is required on the surface of the solid electrolyte 1 on the anode side, and the cost can be reduced. In addition, when a certain amount of diesel particulate is deposited and purification is required, power is automatically applied, reducing running costs.

[0026] The purification device shown in FIG. 3 performs the simultaneous treatment of diesel particulates by the purification device shown in FIG. 1 (FIG. 2) and nitrogen oxide treatment using an oxidation catalyst simultaneously. . The nitrogen oxides to be treated are contained in the exhaust gas along with diesel particulates. In this purification device, an adsorbent 5 and an oxidation catalyst 6 are provided on one surface 10 side of the solid electrolyte 1 of the purification device shown in FIG. In other words, this apparatus is provided on the solid electrolyte 1 having oxygen ion conductivity, the application means 2 for applying a voltage between both surfaces of the solid electrolyte 1, and the one surface 10 side of the solid electrolyte 1, and adsorbs nitrogen oxides. An adsorbent 5 to be formed and an oxidation catalyst 6 provided on one side 10 of the solid electrolyte 1.

[0027] The solid electrolyte 1 is the same as that shown in FIG. The applying means 2 applies a voltage so that the side 10 of the solid electrolyte 1 on which the diesel particulates are deposited becomes the anode side. In this apparatus, the first electrode 3 provided on the one surface 10 side of the solid electrolyte 1 is preferably constituted by a porous electrode including the oxidation catalyst 6. For example, the first electrode 3 is made of porous platinum or silver. That is, the first electrode 3 is used together as the oxidation catalyst 6. In FIG. 3, a nitrogen compound adsorbent 5 is laminated on the first electrode 3 (oxidation catalyst 6) in a net shape. The adsorbent 5 can be an alkaline earth metal or an alkali metal, and can include, for example, norium. The adsorbent 5 shown in FIG. 3 is formed in layers.

[0028] A purification method using this purification apparatus shown in FIG. 3 is as follows. First, the same as Fig. 1 (Fig. 2) Similarly, a voltage is applied between both surfaces of the solid electrolyte 1 by the applying means 2 to supply oxygen ions from the force sword side to the anode side. The oxidized ions oxidize (2C + 0 → 2CO) the solid carbonaceous fine particles M in the diesel fine particles present on the deposition surface 12 on the anode side of the solid electrolyte 1 to obtain carbon oxides containing carbon monoxide. (Arrow a). The diesel particulates having the solid carbon particulates M are contained in the exhaust gas, and are deposited on the deposition surface 12 on the one side 10 side of the solid electrolyte 1. The deposition surface 12 becomes the outer surface of the first electrode 3 having the oxidation catalyst 6 and the outer surface of the adsorbent 5.

[0029] Then, nitric oxide contained in the exhaust gas together with diesel particulates is oxidized (NO + O → NO + ○ *) by the oxidation catalyst 6 on the anode side of the solid electrolyte 1 to form nitrogen dioxide (arrow b). -1 and arrow b-2). The oxygen used in this oxidation is mainly oxygen contained in the exhaust gas. Then, the nitrogen dioxide is adsorbed on the adsorbent 5. Further, the adsorbed nitrogen dioxide is reduced (2NO + 4CO → N + 4CO) with carbon monoxide obtained by oxidizing the solid carbonaceous fine particles M, using nitrogen dioxide as nitrogen and carbon monoxide as carbon dioxide. (Arrow c). As described above, diesel particulates (solid carbonaceous particulates M) and nitrogen oxides (nitrogen monoxide) contained in the exhaust gas are continuously purified into nitrogen and carbon dioxide.

[0030] The oxidation of the solid carbonaceous fine particles M in the diesel fine particles is promoted by the oxidation catalyst 6 present on the deposition surface 12 of the diesel fine particles. In addition, when nitric oxide is oxidized to nitrogen dioxide (NO + O → NO + O *) (arrow b-1), the oxidation of solid carbonaceous fine particles M is promoted by the active oxygen (○ *) generated. .

[0031] In this way, the solid electrolyte 1 having oxygen ion conductivity and the application of applying a voltage between both surfaces of the solid electrolyte 1 such that one side of the solid electrolyte 1 on which the diesel particulates are deposited becomes the anode side. According to the configuration comprising the means 2, the adsorbent 5 provided on one side of the solid electrolyte 1 for adsorbing nitrogen oxides, and the oxidation catalyst 6 provided on the one side of the solid electrolyte 1, the solid electrolyte Oxygen ions can be supplied from the force sword side to the anode side through the solid electrolyte 1 by applying a voltage between the both surfaces of 1 by applying means 2. Thereby, the solid carbonaceous fine particles M in the diesel fine particles deposited on the anode side can be oxidized to form carbon oxides containing carbon monoxide. Furthermore, oxidation catalyst 6 Nitric oxide contained in the exhaust gas can be oxidized to nitrogen dioxide. Further, the nitrogen dioxide can be adsorbed on the adsorbent 5. Then, the nitrogen dioxide adsorbed on the adsorbent 5 is reduced with carbon monoxide obtained by oxidizing the solid carbonaceous fine particles M in the diesel fine particles into nitrogen gas, and the carbon monoxide is converted into carbon dioxide. Can do. Therefore, it is possible to simultaneously purify both the solid carbonaceous fine particles M and the nitrogen oxides in the diesel fine particles. For example, the exhaust gas purification is performed by setting the surface of the solid electrolyte 1 on the power sword side to the atmospheric side (atmosphere release side) and the surface of the solid electrolyte 1 on the anode side to the exhaust gas side containing diesel particulates. Can do.

[0032] Further, the applying means 2 of this purification device has switching means for periodically inverting the polarity of the applied voltage. That is, the first electrode 3 on the anode side is set to the force sword side, and the second electrode 4 on the cathode side is switched to the anode side, and this switching is performed continuously. FIG. 4 shows a state in which the first electrode 3 is on the force sword side and the second electrode 4 is on the anode side. As a result, the active oxygen (O *) generated on the surface 10 side of the solid electrolyte 1 that is the exhaust gas side G is forced to return to the other surface 11 side of the solid electrolyte 1 that is the atmosphere side A.

[0033] This is to suppress the resynthesis of nitrogen and nitric oxide (N + 20 * → 2NO, NO + O * → NO) by active oxygen. As a result, simultaneous purification of diesel particulates and nitric oxide can be performed in a well-balanced manner. In other words, even though nitrogen dioxide adsorbed on the adsorbent 5 is reduced to produce nitrogen, it is suppressed from being oxidized again with active oxygen to form nitrogen oxide! . The switching means of the application means 2 can be constituted by electrical means, and the frequency and switching time can be changed according to the amount of active oxygen on the exhaust gas side G.

[0034] Thus, according to the configuration in which the applying means 1 has the switching means for periodically reversing the polarity of the applied voltage! /, The polarity is reversed so that the other surface side of the solid electrolyte 1 ( By setting the atmosphere side to the anode side, excess active oxygen can be moved to the force sword side out of the active oxygen generated when adsorbing the nitrogen monoxide contained in the exhaust gas to the adsorbent 5. . As a result, the nitrogen gas obtained by reducing the nitrogen dioxide adsorbed on the adsorbent 5 on one side of the solid electrolyte 1 that is the side intended for purification is converted into nitrogen oxides again by active oxygen. It becomes possible to suppress. Next, FIG. 5 is a schematic diagram showing a purification system that purifies exhaust gas from a diesel engine. This exhaust gas contains diesel particulates (solid carbonaceous particulates M) and nitrogen oxides (nitrogen monoxide). This purification system includes an exhaust passage 7 connected to an exhaust port of a diesel engine (diesel engine) 15 and exhausting exhaust gas, and an exhaust gas purification device 8 provided in a part of the exhaust passage 7. ing. Further, the exhaust passage 7 shown in FIG. 5 is constituted by an exhaust pipe. An exhaust gas purification chamber 16 having an exhaust gas purification device 8 is provided in the middle of the exhaust pipe. A plurality of solid electrolytes 1 are provided in the exhaust gas purification chamber 16. The solid electrolyte 1 is the same as that shown in FIG.

The exhaust gas purification device 8 is connected to the control device 17. The control device 17 is provided with the switching means for periodically reversing the polarity of the applied voltage of the application means 2 and the application means 2, and controls the operation of the purification device 8. Further, the purification device 8 has a charging device 18. The charging device 18 charges the diesel particulates contained in the exhaust gas and deposits the diesel fine particles on the deposition surface 12 (see FIG. 3) of the solid electrolyte 1.

The exhaust gas purification device 8 includes a plurality of solid electrolytes 1. In each solid electrolyte 1, as in the purification device shown in FIG. 3, an adsorbent 5 that is provided on the first surface 10 side of the stationary electrolyte 1 and adsorbs nitrogen oxides, and is provided on the first surface 10 side of the solid electrolyte 1. The oxidation catalyst 6 and the application means 2 for applying a voltage between both surfaces of the solid electrolyte 1 are provided. The applying means 2 is shared by a plurality of solid electrolytes 1. Each solid electrolyte 1 has oxygen ion conductivity, and is provided so that one side 10 is in contact with exhaust gas from the exhaust flow path 7 and the other side 11 is in contact with oxygen in the atmosphere. . The application means 2 is provided on both sides of the solid electrolyte 1 so that the first electrode 3 provided on the first surface 10 side of the solid electrolyte 1 is the anode side and the second electrode 4 provided on the other surface 11 side is the force sword side. A voltage is applied between them. Note that the solid electrolyte 1, the adsorbent 5, the oxidation catalyst 6, and the applying means 2 included in the exhaust gas purification device 8 are the same as those described with reference to FIGS. For example, the applying means 2 has switching means for periodically inverting the polarity of the applied voltage.

FIG. 6 is a configuration diagram of a main part of the exhaust gas purification device 8 provided in the purification system of FIG.

This purification device 8 has a plurality of solid electrolytes 1. In FIGS. 5 and 6, a plurality of (seven in FIG. 6) flat panel-shaped solids are disposed in the exhaust gas purification chamber 16 connected to the exhaust flow path 7. The electrolytes 1 are arranged so as to face each other with a gap between them. The solid electrolytes 1 are alternately turned over to form a laminated structure, and are arranged so that the one surfaces 10, 10 of the adjacent solid electrolytes 1, 1 or the other surfaces 11, 11 face each other. A rod-like spacer member 19 is provided in each gap. A solid electrolyte layer 20 is formed by the plurality of solid electrolytes 1. This solid electrolyte layer 20 is provided in the exhaust gas purification chamber 16.

[0039] An exhaust gas flow path 21 or an air flow path 22 is formed in each gap between the plurality of solid electrolytes 20 and between the spacer members 19 and 19. That is, the exhaust gas flow paths 21 and the air flow paths 22 are alternately formed in order from one side of the solid electrolyte layer 20 in the stacking direction (the lower part in FIG. 6). Note that the exhaust gas flow path 21 is formed between the surfaces 10 and 10 of the adjacent solid electrolytes 1 and 1, and the air flow path 22 is formed between the other surfaces 11 and 11 of the adjacent solid electrolytes 1 and 1.

The direction of the spacer member 19 in the gap constituting the exhaust gas flow path 21 and the direction of the spacer member 19 in the gap constituting the air flow path 22 may be the same direction (not shown). ) Or change direction at a certain angle. In FIG. 6, the spacer member 19 in the gap constituting the air flow path 22 is provided with a 90 ° orientation changed with respect to the spacer member 19 of the exhaust gas flow path 21. As a result, the exhaust gas flow path 21 penetrating in the exhaust gas flow direction (arrow g direction) and the air flow path 22 penetrating in the direction orthogonal to the exhaust gas flow direction (arrow a direction) alternate. Formed. Then, the exhaust gas flowing from the exhaust flow path 7 is directly sent to the exhaust gas flow path 21 as it is, and the air flow path 22 is communicated with the atmosphere side A outside the exhaust gas purification chamber 16 so that the air Is sent to the air flow path 22. As a result, when the exhaust gas passes through the exhaust gas passage 21, the diesel particulates contained in the exhaust gas face the exhaust gas passage 21. Is deposited and oxidized, and nitrogen oxides in the exhaust gas are reduced.

FIG. 7 shows a modification of the exhaust gas purification device 8. A plurality of cylindrical solid electrolytes 1 are provided in a cylindrical exhaust gas purification chamber 16 having a rectangular cross section penetrating in the flow direction of the exhaust gas flowing in the exhaust flow path 7 (arrow g direction). The solid electrolyte 1 is formed in a cylindrical shape so that the other surface 11 side that is the atmosphere side A is the inner surface. The outer peripheral surface of the solid electrolyte 1 in the form of a cylinder is the exhaust gas side G on one side 10 side and the deposition surface 12. And cylindrical solid The axial direction of the body electrolyte 1 is the direction (arrow a direction) perpendicular to the flow direction of the exhaust gas (arrow g direction). These solid electrolytes 1 are provided in the exhaust gas purification chamber 16 so as to have a mutual gap.

Thereby, the inside of the cylindrical solid electrolyte 1 communicates with the atmosphere side A, and air can pass through the inside of the cylindrical solid electrolyte 1. The exhaust gas flowing from the exhaust passage 7 flows through the gap between the cylindrical solid electrolytes 1, 1, and the diesel particulate force contained in the exhaust gas passing through the gap is the outer peripheral surface of the cylindrical solid electrolyte 1. It is deposited on the side deposition surface 12 and oxidized, and nitrogen oxides in the exhaust gas are reduced.

[0041] In the exhaust gas purification device 8 shown in Figs. 6 and 7, the diesel particulates in the exhaust gas introduced into the exhaust gas purification chamber 16 are charged by the charging device 18 (see Fig. 5) to obtain a solid electrolyte. Diesel particulates are actively collected on the deposition surface 12 of 1. That is, the charging electrode is provided in the upstream portion where the exhaust gas flows into the exhaust gas purification device 8. Then, by setting the electrode 3 (see Fig. 3) on the deposition surface 12 side of the solid electrolyte 1 to the ground level, an electric field is formed and the diesel particulates are charged, and the charged diesel particulates are efficiently converted into the solid electrolyte. Dust is collected on 1 accumulation surface 12.

In addition, the exhaust gas purification device 8 shown in FIG. 7 is arranged such that the outer peripheral surface serving as the deposition surface 12 of the cylindrical solid electrolyte 1 partially blocks the exhaust gas. For this reason, exhaust gas is sprayed directly on the outer peripheral surface, and diesel particulates in the exhaust gas are efficiently collected on the outer peripheral surface of the solid electrolyte 1 by its inertial force. Furthermore, since there is only the solid electrolyte 1 that can purify the exhaust gas in the exhaust gas purification chamber 16, the concentration of diesel particulates in the exhaust gas, where there is no risk of diesel particulates accumulating on other parts and blocking the flow path, It is effective when it is high.

FIG. 8 and FIG. 9 show still another modification of the exhaust gas purification device 8. The solid electrolyte 1 of the purification device 8 is formed in a U-shaped cross section. The solid electrolyte 1 is composed of a side wall 23 extending from the opening to the back and a back wall 24 having a butting shape at the back. The side wall 23 is in a direction parallel to the flow direction of the exhaust gas flowing from the exhaust passage 7 (arrow g direction). A plurality of solid electrolytes 1 are provided in the exhaust gas purification chamber 16 so that the back wall 24 has a surface orthogonal to the flow direction of the exhaust gas. And a solid electrolyte with a U-shaped cross section 1 The inner surface is the deposition surface 12 on the side 10 shown in FIG. 3, and the outer surface of the solid electrolyte 1 is the atmosphere side A. The U-shaped solid electrolyte 1 can be formed into a bottomed cylindrical shape having a circumferential side wall 23 and a back wall 24. Furthermore, the solid electrolyte 1 having a U-shaped cross section is connected to the adjacent solid electrolyte 1 by a connecting wall member 25, and the connected solid electrolyte 1 allows the exhaust gas purification chamber 16 to be connected to the exhaust gas side G space. It is divided into the atmosphere side A space.

Furthermore, a pipe-like exhaust conduit 26 is inserted inside the solid electrolyte 1 having a U-shaped cross section with a gap from the inner side surface of the solid electrolyte 1. The exhaust gas flowing from the exhaust passage 7 is guided to the back wall 24 side of the solid electrolyte 1 by the exhaust conduit 26. The induced exhaust gas collides with the back wall 24 of the solid electrolyte 1, and then flows between the outer peripheral surface of the exhaust conduit 26 and the side wall 2 3 of the solid electrolyte 1, and the exhaust gas purified by the solid electrolyte 1 is It is discharged outside the exhaust gas purification chamber 16. Note that an air inlet 27 and its outlet 28 are provided in the portion on the atmosphere side A of the exhaust gas purification chamber 16 partitioned by a plurality of connected solid electrolytes 1.

Further, in the exhaust gas purification device 8, as shown in FIG. 8, the diesel particulates are charged by the charging device 18 and the diesel particulates are collected on the deposition surface 12 of the solid electrolyte 1. In this case, the exhaust conduit 26 is used as a charging electrode, and the electrode 3 (see FIG. 3) on the deposition surface 12 side of the solid electrolyte 1 is set to the ground level. As a result, electrolysis is formed between the outer peripheral surface of the exhaust conduit 26 and the inner surface of the solid electrolyte 1. When the exhaust gas passes through this period, diesel particulates in the exhaust gas are charged, and the charged diesel particulates are efficiently collected on the deposition surface 12 of the solid electrolyte 1. Then, the diesel particles deposited on the deposition surface 12 are purified.

A purification method using the exhaust gas purification device 8 shown in FIG. 9 will be described. The exhaust gas flowing from the exhaust passage 7 first flows in the exhaust conduit 26. Diesel particulates in the exhaust gas that has passed through the exhaust pipe 26 are trapped on the deposition surface 12 of the back wall 24 of the solid electrolyte 1 by its inertial force. The exhaust gas further flows between the exhaust pipe 26 and the solid electrolyte 1, and diesel particulates charged by the charging device 18 between them are separated from the side wall 23 of the solid electrolyte 1 by the electric field formed by the charging device 18. Collected on the deposition surface 12 at That is, the exhaust gas purifying device 8 has an inertia collecting action at the back wall 24 of the solid electrolyte 1 due to the inertia force of the exhaust gas and an electric collecting action by the charging device 18. Diesel particulates with large particle diameters are effective for inertial collection, and those with small particle diameters are effective for electric collection. These two actions make diesel particulates with various particle sizes more efficient. It can be collected well.

Next, still another embodiment of the purification device will be described with reference to FIG. This purification apparatus is a modification of the purification apparatus shown in FIGS.

FIG. 10 is a model diagram showing the purification device. This device can also purify exhaust gas exhausted from diesel engine power, and can purify solid carbonaceous particulates M and nitrogen oxides in diesel particulates contained in the exhaust gas. The purifying device includes a solid electrolyte 1 having ionic conductivity and capable of supplying oxygen ions to one side, and a first electrode 3 provided on one side 10 and the other side 11 of the solid electrolyte 1, respectively. A purification structure 30 having a second electrode 4 is provided.

The solid electrolyte 1 has a panel shape, and the purification structure 30 is configured by laminating the first electrode 3 on one surface 10 and the second electrode 4 on the other surface 11. As the solid electrolyte 1, for example, one used in a fuel cell can be applied, and a force S can be moved by causing a potential difference between both ends of the solid electrolyte 1. As long as this solid electrolyte 1 can give oxygen ions to the first electrode 3 as a result, the ions that move through the solid electrolyte 1 are not limited to oxygen ions.

[0049] The purification structure 30 is made porous so that gas containing nitrogen oxide can be permeated except for diesel particulates (solid carbonaceous particulates M) from the exhaust gas to be purified. . That is, the solid electrolyte 1 in the purification structure 30 is porous, and the first electrode 3 and the second electrode 4 are porous electrodes. By making the purification structure 30 porous, exhaust gas containing diesel particulates is passed from the first electrode 3 side to the second electrode 4 side (arrow F), thereby capturing diesel particulates on the first electrode 3 side. It is possible to collect (filter).

[0050] Similarly to the purification apparatus shown in FIG. 1, the solid electrolyte 1 in which a potential difference is generated is used. Then, the trapped diesel particulate solid carbonaceous particles M are oxidized by oxygen ions applied to the first electrode 3 side.

Further, the exhaust gas that has passed through the purification structure 30 contains nitrogen oxides. This nitrogen oxide is reduced on the second electrode 4 side as will be described later. In other words, in the purification structure 30, the first electrode 3 side is an oxidation part that oxidizes the solid carbonaceous fine particles M, and the second electrode 4 side that is the opposite side (back side) across the solid electrolyte 1 is the purification structure. It becomes a reducing part that reduces nitrogen oxides contained in the exhaust gas that has permeated through the body 30. In other words, this purification device can purify the solid carbonaceous fine particles M on one surface side of the purification structure 30 and simultaneously purify nitrogen oxides on the other surface side.

In this case, by moving oxygen ions in the solid electrolyte 1, the solid carbonaceous fine particles M in the unburned fine particles can be oxidized into carbon oxides in the oxidation part on the first electrode 3 side. . At the same time, in the reducing part on the second electrode 4 side, the solid electrolyte 1 moves oxygen ions from the second electrode 4 side to the first electrode 3 side, thereby passing the exhaust gas that has permeated the purification structure 30. Nitrogen oxides contained in can be reduced to nitrogen gas. Thus, simultaneous purification (simultaneous decomposition) of solid carbonaceous fine particles M and nitrogen oxides in the exhaust gas becomes possible.

[0051] The purification structure 30 is connected to a control means 31 provided for performing such a purification process. The control means 31 has an application means 2 similar to that shown in the purification device of FIG. More specifically, the control means 31 is provided with the application means 2 that can apply a voltage so that the first electrode 3 side becomes the anode side, and a resistor provided in parallel with the application means 2, and the control means 31 as a whole. And a bypass circuit section 34 capable of forming a closed circuit. Further, the control means 31 switches between the state where the voltage is applied between the electrodes 3 and 4 by the applying means 2 and the state where the application is stopped between the electrodes 3 and 4 and the closed circuit is configured. And a switching control unit 35 that can be used.

That is, when the exhaust gas temperature varies depending on the operating conditions of the diesel engine and the exhaust gas temperature is low, a voltage is applied between the electrodes 3 and 4 by the application means 2 so that the first electrode 3 side becomes the anode side. By doing so, it is possible to move ions in the solid electrolyte 1 and to perform the simultaneous purification. However, when the exhaust gas temperature rises due to a large engine load, etc., the solid carbonaceous fine particles M are easily oxidized on the first electrode 3 side of the purification structure 30 and the solid electrolyte 1 operates as a fuel cell. Can be made. As a result, the ions can move in the solid electrolyte 1 without supplying electric energy from the outside (by the applying means 2), and the simultaneous purification is performed. That is, when the exhaust gas temperature is high and the ionic conductivity in the solid electrolyte 1 is high, the switching control unit 35 includes the solid electrolyte 1 as a state where the electrodes 3 and 4 are connected by the bypass circuit unit 34. By configuring a closed circuit that does not act on external voltage, it is possible to move ions within the solid electrolyte 1.

[0053] The control means 31 is connected to a temperature sensor (not shown) for measuring the temperature of the exhaust gas. The switching control unit 35 is configured to perform switching operation according to the output of the temperature sensor. In other words, when the temperature of the exhaust gas is low, a voltage is applied between the electrodes 3 and 4 so that it is in a state of! /, And when the temperature is high, a closed circuit is formed! The mode is automatically switched to. This can reduce power consumption and increase energy efficiency. In addition, the switching of these states may be other than by means of detecting the temperature of the exhaust gas by a temperature sensor, and the solid electrolyte 1 has an ion conductive function to such an extent that the simultaneous purification can be performed. It may be determined by detecting whether or not the fuel cell can be operated.

[0054] The exhaust gas purifying method performed by this purifying device is such that the exhaust gas containing diesel particulates is passed from one side 10 side to the other side 11 side of the solid electrolyte 1 made of porous material. Collect on the 10th side. Then, a predetermined potential difference is generated between both surfaces of the solid electrolyte 1. As a result, the ions are moved from the other surface 11 side of the solid electrolyte 1 to the first surface 10 side so as to give oxygen ions to the first surface 10 side, and the diesel particulates collected on the first surface 10 side are collected by this ion. Oxidize. In FIG. 10, oxygen present in the other surface 11 side of the solid electrolyte 1 or oxygen atoms in the nitrogen oxide are moved as oxygen ions in the solid electrolyte 1, and the oxygen ions are moved to the first surface 10 side. Supplying to electrode 3 side. As a result, carbon contained in the solid carbonaceous fine particles M in the collected diesel particulates is continuously oxidized to carbon dioxide (C + O → CO), and solid carbon The fine particles M are purified (decomposed). The obtained carbon dioxide passes through the purification structure 30 together with the exhaust gas flowing from the upstream side, flows to the second electrode 4 side, which is the downstream side, and further further downstream than the purification structure 30. Discharged.

[0055] Further, nitrogen oxides contained in the exhaust gas that has passed through the purification structure 30 are purified on the second electrode 4 side (reduction part).

FIG. 11 is a diagram for explaining the mechanism by which nitrogen oxides are purified on the second electrode 4 side. Ceria or ceria oxide is supported on the second electrode 4 side (force sword side) of the purification structure 30. ing.

The purification method performed in this reduction unit is as follows. Ceria (ceria oxide) is a stable state of CeO in dilute operation (CeO + 1/20 → 2CeO: oxygen storage effect by ceria). However, when voltage is applied by the application means 2, oxygen is released on the second electrode 4 side, and Ce 2 O can be kept stable in the lean operation state (2

CeO + 2e— → Ce O + 〇 ² ). At this time, oxygen ions are generated, and the oxygen ions are moved to the first electrode 3 side by the solid electrolyte 1, and the oxygen ions are used for oxidation of the solid carbonaceous fine particles M. And ceria can reduce nitrogen oxide (NO) in this state (Ce 2 O + NO 2CeO + 1 / 2N).

FIG. 12 is a diagram illustrating another mechanism for purifying nitrogen oxides on the second electrode 4 side. An adsorbent 5 for adsorbing nitrogen oxide is supported on the second electrode 4 (force sword side) of the purification structure 30. The adsorbent 5 is the same as that in the purification apparatus of FIG. 3, and is an alkaline earth metal or an alkali metal. Specific examples include calcium, strontium, barium, radium, lithium, sodium, potassium, norevidium, cesium, and francium. Of these, calcium, strontium, norlium and potassium are preferred in terms of stability and other properties and costs. Further, an oxidation catalyst 6 is supported on the second electrode 4 as in FIG. The oxidation catalyst 6 includes platinum and silver. The porous second electrode 4 itself contains platinum or silver, or the porous second electrode 4 itself is made of platinum or silver to form an acid hornworm medium 6 with a force S. Monkey.

Then, barium oxide as the adsorbent 5 becomes a stable state (barium carbonate) by reaction with carbon dioxide on the second electrode 4 side (BaO + CO → BaCO 3). [0057] The purification method performed in the reduction unit is as follows. The exhaust gas that has passed through the purification structure 30 contains nitrogen monoxide and oxygen. On the second electrode 4 side, the nitric oxide is oxidized (NO + 0 → NO + 0 ² —) by the oxidation catalyst 6. It becomes nitrogen dioxide. At this time, oxygen ions are generated. The oxygen ions are moved to the first electrode 3 side by the solid electrolyte 1, and the oxygen ions are used for oxidation of the solid carbonaceous fine particles M.

The nitrogen dioxide and nitrogen dioxide contained in the exhaust gas are adsorbed on the adsorbent 5 (BaCO + 2NO + 0 → Ba (NO) + CO), and the voltage is applied by the application means 2.

3 2 3 2 2

Nitrogen dioxide is reduced by carrying out calorie (Ba (NO) + 2e— → BaO + N + 2 o + o ² ).

11 and FIG. 12, oxygen ions generated on the second electrode 4 side can be forcibly moved to the first electrode 3 side by the solid electrolyte 1. For this reason, it can suppress that the nitrogen obtained by reduction | restoration is re-synthesize | combined to a nitrogen oxide.

As described above, this purification method is an electrochemical reduction method rather than a method using a reducing substance such as carbon monoxide.

In each embodiment, the voltage application by the application unit 2 may always be applied as a constant voltage, but the application state of the voltage is changed or varied periodically by the action of the control unit 31. May be. For example, it can be periodically changed between a state where a voltage is applied and a state where a voltage is not applied. That is, after a certain amount of solid carbonaceous fine particles M is deposited on the first electrode side 3 of the purification structure 30, the purification treatment may be performed intermittently by applying a voltage for a predetermined time. .

[0059] According to the purification device as described above, the exhaust gas is forced to flow in from the first electrode 3 side and discharged to the second electrode 4 side by the pressure of the exhaust gas. Since the purification structure 30 is porous, particulate matter such as diesel particulates (solid carbonaceous particulate M) in the exhaust gas is collected on the first electrode 3 side. That is, the particulate matter in the exhaust gas is automatically collected on the first electrode 3 side by the filtering effect of the purification structure 30. This eliminates the need to collect diesel particulates on the electrode surface using an electrostatic precipitator, thereby reducing the cost and size of the device. The exhaust gas from which the fine particles are collected and removed on the first electrode 3 side passes through the purification structure 30 and flows out to the second electrode 4 side. For example, as shown in FIG. Nitrogen oxides are occluded and decomposed by occlusion of nitrogen oxides by the alkali earth metal and nitrogen oxide reduction action by the reaction at the second electrode 4, and the oxygen ions generated at this time are decomposed. (Active oxygen) is forcibly removed to the first electrode 3 side through the solid electrolyte 1 to which a voltage is applied. This suppresses NOx recombination on the second electrode 4 side, promotes oxidation of the fine particles collected on the first electrode 3 side, and allows simultaneous purification of nitrogen oxides and solid carbonaceous fine particles M. It becomes.

[0060] DPNR, which has been known as a conventional purification device, has a force S, which is a NOx occlusion reduction catalyst supported on a ceramic filter, and the amount of solid carbonaceous fine particles M emitted relative to the amount of NOx normally emitted. Will increase. Therefore, it is necessary to add the reducing agent to the exhaust gas, and a configuration such as providing the addition device in the exhaust system is separately required. However, according to this purification device, the purification of the solid carbonaceous fine particles M and NOx is performed independently on each of the one side and the other side of the purification structure 30. For this reason, it can be processed independently without depending on the balance between the solid carbonaceous fine particles M and NOx in the exhaust gas, and the addition of a reducing agent is unnecessary. Therefore, since this purification device can be simplified and made compact, it can be retrofitted to existing automobiles.

[0061] Further, the force S containing sulfur in the exhaust gas, this sulfur may adversely affect the reduction treatment of nitrogen oxides. However, when this sulfur is contained in the diesel particulates, this purification device collects the diesel particulates containing sulfur on the first electrode 3 side of the purification structure 30 and the second electrode on the back side thereof. Since nitrogen oxide is reduced on the 4th side, fine particles containing sulfur are not deposited on the nitrogen oxide reduction electrode, so that the influence of sulfur can be suppressed.

The solid electrolyte 1 used in the purification device shown in FIGS. 1 to 4 and the porous purification structure 30 used in the purification device shown in FIG. 10 will be further described. Examples of the solid electrolyte 1 to be used include conventionally known yttrium-stabilized zirconia (zirconia-based electrolyte YSZ), ceria-based solid electrolyte (SDC), or molten carbonate type. In the case of a zirconium oxide electrolyte, sufficient oxygen ions can be supplied at a high exhaust temperature of 350 ° C or higher. And if the exhaust temperature is high (eg 350 ° C) In order to cause oxidation (combustion) of diesel particulates by supplying oxygen ions effectively even when the temperature is too low (for example, 250 ° C to 300 ° C) or below 250 ° C, the solid electrolyte 1 Ionic conductivity can be improved by changing the shape and thickness. Note that the solid electrolyte 1 having oxygen ion conductivity described above generally has a force S that increases the oxygen ion conductivity at a high temperature and facilitates the movement of oxygen ions, and conversely becomes difficult at a low temperature. If a high applied voltage is forcibly applied to the low-temperature solid electrolyte 1, the oxygen constituting the solid electrolyte 1 is forced to move, resulting in deterioration of the electrolyte 1. Therefore, the solid electrolyte 1 is heated to keep the temperature of the solid electrolyte 1 at about 330 ° C to 370 ° C, or the gas temperature on the exhaust gas side G is set to about 330 ° C to 370 ° C. It is preferable to keep it configured. Then, by lowering the voltage applied by the applying means 2 to 1 to 10 volts, the solid electrolyte 1 is prevented from deteriorating, and oxygen ions are supplied efficiently and at a sufficient speed.

Next, specific specifications of the purification structure 30 shown in FIG. 10 will be described. The purification structure 30 as a whole can be collected (filtered) on one side with diesel particulates (solid carbonaceous particulate M), and exhaust gas other than this can be collected on one side. However, it is made porous with a network structure made up of numerous continuous pores so that it can permeate to the other side.

The first electrode 3 serving as a decomposition electrode for diesel particulates has a thickness of 1 μm or more and 5 mm or less, preferably 5 m or more and 50 m. If the thickness is too thin, the capture rate of the diesel fine particles may be reduced, and if it is too thick, the pressure loss may be increased. The average pore diameter of the porous first electrode 3 is 0.5 111 or more and 100 Hm or less, preferably 1 Hm or more and 10 m, and the porosity is 1 It is preferably 0% or more and 80% or less, more preferably 40% or more and 60% or less. If these values are too small, the pressure loss may increase, and if they are too large, the diesel particulate collection rate may decrease.

The thickness of the solid electrolyte 1 is preferably 1 μm or more and 5 mm or less, more preferably 10 am or more and 500 am. If this thickness is too thick, the pressure loss may increase. The average pore size of the pores (cavities) in the porous solid electrolyte 1 is 0.5 m or more and 100 The porosity is preferably 1 μm or more and preferably 30 μm or more, and the porosity is preferably 10% or more and 80% or less, more preferably 40% or more and 60% or less. If these values are too small, the pressure loss may increase. If it is too large, the ion conductivity per unit area may decrease.

The thickness of the second electrode 4 serving as a decomposition electrode of nitrogen oxide is preferably 1 μm or more and 5 mm or less, more preferably 5 m or more and 50 m. If this thickness is too thick, the pressure loss may increase. The average pore diameter of the pores (cavities) in the porous second electrode 4 is 0.5 Hm or more and 100 Hm or less, preferably 1 μm or more and 30 μm, and the porosity is It is preferably 10% or more and 80% or less, more preferably 40% or more and 60% or less. If these values are too small, the pressure loss may increase.

In addition, both or one of the average pore diameter and the porosity of the first electrode 3 may be smaller than that of the solid electrolyte 1 and the second electrode 4. That is, the pressure loss of the exhaust gas flowing through the solid electrolyte 1 and the second electrode 2 is reduced while maintaining the collection rate of diesel particulates at the first electrode 3.

[0064] In order to efficiently transmit the exhaust gas in which diesel particulates are collected on the first electrode 3 side to the purification structure 30, the pressure loss in the purification structure 30 is reduced. preferable. This is because a large pressure loss causes a decrease in engine output and fuel consumption. The appropriate value of the pressure loss in the purification structure 30 depends on the thickness, the average pore diameter, and the porosity, and the force S and the diesel particulates that differ depending on the diesel particulate deposition state and the exhaust gas flow rate are accumulated. It is preferable that the pressure is 20 kPa or less in the state (new state). Further, in order to reduce the pressure loss, it is necessary to make the porosity so as not to decrease the trapping rate of diesel particulates on the first electrode 3 side by excessively increasing the porosity. The diesel particulate collection rate on the first electrode 3 side is preferably porous so that it can be 90% or more.

[0065] A method for producing the porous purification structure 30 will be described. A conventionally known method can be applied to the method of making the solid electrolyte 1 and the electrode porous. For example, it is possible to obtain the strength S obtained by firing the solid electrolyte 1 and the electrodes 3 and 4, and there are a method of scattering the fine molten material (pellet) contained during the firing, a method using a foaming agent, and the like. is there. The porous material thus obtained is formed by innumerable holes (cavities) that are continuous from one surface side to the other surface side so as to be permeable to exhaust gas excluding diesel particulates.

[0066] A more preferable form of the purification structure 30 will be described. Each of the first electrode 3 and the second electrode 4 can contain platinum or silver, or the electrode can be made of platinum or silver. Particularly preferred is silver. This is because, since silver has an oxygen adsorption capacity, there are many active sites that oxidize (decompose) the solid carbonaceous fine particles M at the first electrode 3 especially when the first electrode 3 is made of silver. It becomes. Thereby, oxygen ions can be efficiently used for the oxidation of the solid carbonaceous fine particles M, and a high decomposition rate can be obtained.

Further, as a more preferable form of the electrodes 3 and 4, it is preferable that both the first electrode 3 and the second electrode 4, or one of them includes the same material as that of the solid electrolyte 1. In particular, when the first electrode 3 is fired with the solid electrolyte 1, the oxidation reaction (decomposition reaction) of the solid carbonaceous fine particles M occurs at the interface between the first electrode 3 and the solid electrolyte 1. For this reason, the reaction active point for oxidation can be increased by mixing the solid electrolyte material with the electrode material, and the oxidation of the solid carbonaceous fine particles M can be promoted. Furthermore, by providing the adsorbent 5 that adsorbs nitrogen oxides on the second electrode 4 side, which is the reducing part, nitrogen oxides contained in the exhaust gas that has passed through the purification structure 30 are adsorbed on the second electrode 4 side. The nitrogen oxide is reduced by the force S by moving (accumulating) oxygen ions in the solid electrolyte 1 from the second electrode 4 side to the first electrode 3 side.

Further, by including the same material as the solid electrolyte 1 in both the first electrode 3 and the second electrode 4 or one of them, the bonding state between the electrodes 3 and 4 and the solid electrolyte 1 is improved, and the purification structure The durability of 30 can be improved. This is because if the thermal expansion coefficients of the electrodes 3 and 4 constituting the purification structure 30 and the solid electrolyte 1 are significantly different, the temperature change of the purification structure 30 is large in the usage state. 4 may peel off from the solid electrolyte 1. However, if the electrodes 3 and 4 contain the same material as the solid electrolyte 1 and are fired to obtain the purification structure 30, the solid electrolyte 1 and the electrodes 3 and 4 can be integrated, even if a large temperature change occurs. Can be thermally deformed. For this reason, the electrodes 3 and 4 are peeled from the solid electrolyte 1 and the durability of the purification structure 30 can be improved.

[0068] In addition, in order to improve the durability of the purification structure 30, a material to be included in the electrodes 3 and 4 may be a solid-state battery. A material having the same thermal expansion coefficient as that of the solid electrolyte 1 may be included in both or one of the electrodes 3 and 4 that are not exactly the same as the electrolyte 1. From the viewpoint of improving the durability, if the viewpoint of promoting the reaction is included, it is most preferable to include the same material as the solid electrolyte 1 in both the first electrode 3 and the second electrode 4 or one of them.

As described above, the first electrode 3 is a mixture of silver and solid electrolyte 1 (silver cermet), and the adsorbent 5 for adsorbing nitrogen oxides is further provided on the second electrode 4 side which is the reducing portion. It is particularly preferred from the viewpoint of promoting the reaction and improving the durability, and the second electrode 4 is made the same as the first electrode, so that the manufacture is facilitated. As described above, the adsorbent 5 is preferably an alkaline earth metal or an alkali metal.

[0069] Further, in the production of electrodes 3 and 4, the force capable of obtaining a porous silver electrode by firing silver particles. A solid electrolyte material (solid electrolyte particles) is mixed with silver material (silver particles). The porous electrodes 3 and 4 made of a mixture of silver and the solid electrolyte 1 can be obtained by baking. At this time, it is preferable that the particle size of the silver particles and the solid electrolyte particles be 0.01 μm or more and 10 m or less. For example, 1 am silver particles and 0.1 · 1 am solid electrolyte particles are mixed. That's fine. The finer the particles, the larger the surface area of the electrodes 3 and 4 obtained by firing, resulting in an increase in the number of reaction active sites, which can improve the reaction performance (decomposition performance).

[0070] The mixing ratio of the silver material (electrode material) and the solid electrolyte material will be described. When the amount of solid electrolyte material is increased, the interface between silver, which is the active site of reaction, and solid electrolyte 1 increases, and the ability to improve the reaction performance at the electrode. There is a possibility that the conductivity is lowered and the performance as a whole is lowered. Therefore, it is particularly preferable that the solid electrolyte material is 60 vol% or less as a whole. The solid electrolyte material should be 20 vol% or more and 40 vol% or less as a whole! /. Specifically, the solid electrolyte material may be 30 vol%, and the silver material may be 70 vol%.

Next, the mixing ratio of the adsorbent 5 on the second electrode 4 side will be described. When the volume of the second electrode 4 is 100%, it is preferable that the content of norm is 30 vol% or more and 40 vol% or less. Then, it is preferable to have a state in which the norium is dispersed. Normally, barium is supported on the electrode 4 in the form of barium oxide (BaO) particles, but if there is too much barium, a film of barium oxide is formed, and the solid electrolyte 1 serving as a reaction active site Less interface with second electrode 4 There is a risk that the degradation performance will deteriorate. In addition, in the case where the form in which norium is dispersed throughout the second electrode 4 is considered, when the volume of the second electrode 4 is set to 100%, the norm may be set to ΙΟΟνο 1%.

FIG. 15 shows the reduction rate (purification rate) of the solid carbonaceous fine particles M contained in the exhaust gas when a test for purifying the exhaust gas exhausted from the combustor by the purification device of the present invention is performed. It is a graph which shows the relationship with purification time. The conditions for this test were as follows: in the purification structure 30 made of porous material, the solid electrolyte 1 was a ceria-based solid electrolyte, the first electrode 3 was a silver electrode, and the second electrode 4 was a mixture of platinum and the solid electrolyte. (Cermet). The first electrode 3 has a thickness of 30 m, an average pore diameter of 3 m, and a porosity power of ¾0%. In the solid electrolyte 1, the thickness is 0.5 m, the average pore diameter is 5 m, and the porosity is 40%. The second electrode 4 has a thickness of 30 m, an average pore diameter of 3 m, and a porosity of 30%. Then, the temperature of the solid electrolyte 1 is set to 350 ° C, the value of the current flowing to the solid electrolyte 1 by the applying means 2 is set to 0.3 A, and the introduction flow rate of the exhaust gas to the purification structure 30 is set to 1.0 liter / min. The emission concentration of solid carbonaceous fine particles N is 75 mg / m ³ . The amount of the solid carbonaceous fine particles M supplied to the purification structure 30 in 30 minutes is 2.25 g.

According to the results shown in FIG. 15, a high decomposition rate of the solid carbonaceous fine particles M of 94% or more can be obtained after 4 hours from the start of purification, and further 90% after 7 hours. It was confirmed that the above high level and decomposition rate were obtained.

As other test conditions, the solid electrolyte 1 is a zirconia-based electrolyte, the first electrode 3 is a mixture (cermet) of silver and a zirconia-based electrolyte, and the second electrode 4 is platinum and a zirconia-based electrolyte. Even when the mixture (cermet) is used and the other conditions are the same as in FIG. 15, a high decomposition rate can be obtained as in FIG. The durability of the purification structure 30 can be improved by including the same material as the solid electrolyte 1 in the first electrode 3 and the second electrode 4. In this case, the first electrode 3 contains 70 vol% silver and 30 vol% zirconia electrolyte.

[0074] As described above, by including a silver electrode in the first electrode 3, since silver has an oxygen adsorption ability, there is an active site that oxidizes (decomposes) the solid carbonaceous fine particles M in the first electrode 3. Many Will exist. Therefore, oxygen ions can be efficiently used for the oxidation of the solid carbonaceous fine particles M, and a high decomposition rate can be obtained. In order to measure the collection rate of the solid carbonaceous fine particles M in the purification structure 30, a filter (not shown) was provided on the flow path side for discharging the exhaust gas that passed through the purification structure 30. That is, the collection rate in the purification structure 30 was measured from the increase in mass of the filter due to the solid carbonaceous fine particles M collected in this filter. In this test, no increase in mass was confirmed with the filter, and it was confirmed that the collection rate of the solid carbonaceous fine particles M in the purification structure 30 was 100%.

FIG. 16 shows the reduction rate of the solid carbonaceous fine particles M contained in the exhaust gas and the purification structure 30 when a test for purifying the exhaust gas discharged from the combustor by the purification device of the present invention is performed. It is a graph which shows the relationship with the electric current sent through. As conditions for this test, the purification structure 30 is the same as that in the test in FIG. 15, and the value of the current flowing through the solid electrolyte 1 by the application means 2 is made constant from zero to 0.3A. Then, the reduction rate of the solid carbonaceous fine particles M 30 minutes after the start of purification was measured. In this test, the amount of the solid carbonaceous fine particles M supplied to the purification structure 30 in 30 minutes is 2.25 g.

According to the results shown in FIG. 16, it is possible to obtain a decomposition rate of about 30% even when no voltage is applied due to the catalytic action of silver (current value is zero). It was confirmed that a high decomposition rate of 97% was obtained by applying a current of 0.3A.

FIG. 17 shows the reduction rate of nitrogen oxides contained in the exhaust gas and the flow to the purification structure when a test for purifying the exhaust gas discharged from the combustor by the purification device of the present invention is performed. It is a graph which shows the relationship with an electric current. The test conditions were as follows. In the porous purification structure 30, the solid electrolyte 1 was yttrium stabilized zircoua, the first electrode 3 was a mixture of silver and yttrium stabilized zircoure, and the second electrode 4 was the first. It is the same as electrode 3 and is a mixture of silver and yttrium-stabilized zirconium. The first electrode 3 has a thickness of 30 m, an average pore diameter of 2 m, and a porosity of 60%. In the solid electrolyte 1, the thickness is 0.5 m, the average pore diameter is 5 m, and the porosity is 40%. In the second electrode 4, the thickness is 30 m, the average pore diameter is 2 m, and the porosity is 60%. It is. Further, barium is supported as the adsorbent 5 in the second electrode 4. The two-dot chain line in Fig. 17 (Example 1) 1S When the total volume of the second electrode 4 is 100%, barium is 36 vol%, and the one-dot chain line (Example 2) is 26 vol% of norium. It is. The temperature of the solid electrolyte 1 was set to 400 ° C., the flow rate of the exhaust gas introduced into the purification structure 30 was set to 1.0 liter / min, and the concentration of nitrogen oxide NOx was set to 450 ppm. The solid line (Example 3) in Fig. 17 is for the case where the volume of norium is 36 vol% and the exhaust gas introduction flow rate is 0.5 liter / min. Other conditions are the same as the other two. It is. Under each condition, the current value flowing to the solid electrolyte 1 by the application means 2 is made constant while increasing from zero to 0.3 A, and at each current value, the reduction rate of nitrogen oxides NOx 1 minute after the start of purification It was measured.

According to the results shown in FIG. 17, it was confirmed that a high decomposition rate of 80% or more was obtained at a current value of 0.1 A under each condition (Examples;! To 3). Further, in Example 2 and Example 3, it was confirmed that a high decomposition rate of 80% or more was obtained at a low energy of 0.05 mA (4.9 V).

FIG. 13 is a schematic diagram showing a purification system that purifies exhaust gas from a diesel engine. Similar to the purification system shown in FIG. 5, this purification system is connected to the exhaust port of a diesel engine (diesel engine) 15 to discharge exhaust gas, and a part of this exhaust flow path 7. And an exhaust gas purification device 8 provided. The exhaust passage 7 is composed of an exhaust pipe. A cylindrical exhaust gas purification chamber 16 provided in the exhaust gas purification device 8 is provided in the middle of the exhaust pipe. The purification structure 30 is provided inside the exhaust gas purification chamber 16! /.

This exhaust gas purification device 8 is the purification device shown in FIG. The purification structure 30 provided in the purification device 8 includes a solid electrolyte 1 having ionic conductivity and capable of supplying oxygen ions to one surface 10 side, and one surface 10 side and the other surface 11 side of the solid electrolyte 1. Each has a first electrode 3 and a second electrode 4 provided. The purification structure 30 can collect diesel particulates in the exhaust gas on the first electrode 3 side by passing the exhaust gas from the exhaust passage 7 from the first electrode 3 side to the second electrode 4 side. It is assumed to be porous. The control means 31 is connected to the purification structure 30. Then, as described above, the diesel particulates collected on the first electrode 3 side are oxidized, and the nitrogen oxides contained in the exhaust gas that has passed through the purification structure 30 on the second electrode 4 side are reduced. To do.

As shown in FIG. 14, the purification structure 30 interconnects a plurality of cylindrical portions 32 formed in a bottomed cylindrical shape and the openings of the cylindrical portion 32. This is a configuration having a plate-like portion 33. The plate-like portion 33 is attached as a fixed wall to the inner peripheral surface of the exhaust gas purification chamber 16 so as to face the exhaust gas flowing through the exhaust passage 7. The cylindrical portion 32 has the axial direction (exhaust gas flow direction) of the pipe-shaped exhaust gas purification chamber 16 as the axial direction. The inner surface (inner peripheral surface and bottom surface) of the cylindrical portion 32 and the surface of the plate-like portion 33 continuous with the inner surface are the first electrode 3 side. The outer surface (outer peripheral surface and end surface) of the cylindrical portion 32, which is the opposite surface, and the back surface of the plate-like portion 33 continuous with the outer surface are the second electrode 4 side. As a result, the exhaust gas flowing into the exhaust gas purification chamber 16 is transmitted from the surface of the plate-like portion 33 and the inner surface of the cylindrical portion 32 to the opposite surface, and to the first electrode 3 side! /, Diesel particulates are collected and solid carbonaceous particulates M are oxidized. Nitrogen oxides are reduced on the second electrode 4 side, and the treated exhaust gas flows downstream of the exhaust gas purification chamber 16. Discharged.

FIG. 18 is an explanatory view showing a cross section of another embodiment of the purification structure 30 of the present invention. The purification structure 30 further has a support 40. The support 40 is for increasing the mechanical strength of the purification structure 30. As a result, the electrodes 3 and 4 and the solid electrolyte 1 which are other members constituting the purification structure 30 can be thinned. That is, it is not necessary to increase the thickness of the electrodes 3 and 4 and the solid electrolyte 1 in order to increase the mechanical strength of the purification structure. Since the electrodes 3 and 4 and the solid electrolyte 1 can be made thinner, the resistance when the exhaust gas permeates the electrodes 3 and 4 and the solid electrolyte 1 can be reduced, and oxygen ions can be conducted with a small applied voltage. Power can be saved and energy can be saved.

[0081] The support 40 will be specifically described. In FIG. 18, the solid electrolyte 1 formed in the bottomed cylindrical shape is provided on the outer peripheral side of the second electrode 4 formed in the bottomed cylindrical shape, and the first electrode 3 formed in the bottomed cylindrical shape is provided on the outer periphery. It has been. The support 40 is a tube member formed in a bottomed cylindrical shape (or cylindrical shape), and is provided in a laminated state on the inner peripheral side of the second electrode 4. Thereby, the purification structure 30 is formed in a bottomed cylindrical shape. Support 40 Is porous and can transmit exhaust gas permeating from the first electrode 3 side as shown by an arrow. The support 40 has an end mounting portion 40c and a main body portion 40d. The main body portion 40d is in a laminated state with the second electrode 4, and the attachment portion 40c is in a laminated state with the second electrode 4 in a state where the purification structure 30 is present alone before being attached to the fixed wall 47. It is exposed.

[0082] The material of the support 40 is aluminum oxide (alumina), zirconium oxide, mullite (3A1 O

2SiO compounds), stainless steel, and the like. Among them, when the thermal expansion coefficient is close to that of the solid electrolyte 1 and zirconia is used, the temperature change is large, and the purification structure 30 is structurally preferable. It is preferable to do. Further, the thickness of the support 40 is preferably the minimum thickness that can ensure the rigidity of the purification structure 30. For example, when the axial length of the purification structure 30 is 130 mm or more and 170 mm or less, and the outer diameter is 8 mm or more and 12 mm or less, the thickness of the support 40 can be set to 1 mm or more and 2 mm or less. . Also, the average pore diameter of the porous support 40 is preferably larger than the average pore diameter of the solid electrolyte 1 and the electrodes 3 and 4, and the porosity is 40% or more and 50% or less. preferable.

[0083] The purification structure 30 of Fig. 18 will be further described. In the second electrode 4 on the inner diameter side of the solid electrolyte 1, the end of the purification structure 30 on the opening side is exposed to the radially outer side. That is, the second electrode 4 has an exposed surface on the outer peripheral surface of the end portion, and the lead wire of the applying means 2 can be connected to the exposed surface. Thereby, even if the second electrode 4 is thin, the second electrode 4 and the lead wire can be firmly connected. In addition, there is one second connection portion 46 that is a connection portion between the second electrode 4 and the lead wire, and one first connection portion 45 that is a connection portion between the first electrode 3 and another lead wire (one In the purification structure 30 of this), it is preferable to provide the purification structure 30 at a distance. Specifically, it is preferable that the first connection part 45 and the second connection part 46 are provided separately at both ends in the axial direction of the purification structure 30. Furthermore, it is more preferable to provide the first connecting portion 45 and the second connecting portion 46 with a 180 ° phase separation. This is because, when the two connection portions 45 and 46 come close to each other, oxygen ion conduction occurs in the purification structure 30 in the vicinity of these connection portions 45 and 46, and effective oxygen ion conduction occurs in a portion away from these. This is because it may not occur. However, this can be prevented by providing both connecting portions 45 and 46 apart as shown in FIG. In FIG. 18, a metal mesh 48 may be provided as a current collector on the outer periphery of the first electrode 3, and the metal mesh 48 and the lead wire may be connected to form the first connection portion 45. As a result, a voltage can be applied to the entire surface of the first electrode 3, and oxygen ions can be conducted in the entire purification structure 30. The metal mesh 48 can provide a force S provided on the outer periphery of the first electrode 3 and a force S that allows the exhaust gas to permeate. Further, the solid carbonaceous fine particles in the exhaust gas cannot be retained in the metal mesh 48. The mesh is set coarsely. Furthermore, since the support 40 is made of a conductive material, the support 40 integrated with the second electrode 4 can be made to function as a current collector, like the metal net. In other words, a lead wire may be connected to the support 40 to form the second connection portion 46! / (Not shown).

[0085] Note that the support 40 may be in another form, which is not shown, but for example, the support may be provided on the first electrode side (the outer peripheral side of the first electrode). However, in this case, it is necessary to prevent the solid carbonaceous fine particles in the exhaust gas from staying on the support. For example, the support needs to have a coarse mesh structure.

Further, in the exhaust gas purification chamber 16 of the exhaust gas purification device 8 shown in FIG. 13, a fixed wall 47 for attaching the purification structure 30 is provided as shown in FIG. The purification structure 30 can be attached to the exhaust gas purification chamber 16 by fixing the mounting portion 40c that is the exposed shape of the support 40 to the fixed wall 47. Although not shown, a plurality of purification structures 30 can be arranged in parallel on the fixed wall 47 by this mounting structure.

[0086] And, it has such a porous support 40, a solid electrolyte 1, and a first electrode 3 and a second electrode 4 provided on one side and the other side of the solid electrolyte 1, respectively. A method for manufacturing the purification structure 30 will be described with reference to FIG. FIG. 19 illustrates the case where the purification structure 30 has a disk shape.

First, carbon particles and resin are provided on one surface 40a of the support 40, and masking is performed on the one surface 40a. Then, the one surface 40a side is coated with the electrolyte slurry 41, and this is fired to obtain the solid electrolyte 1 on the support body 40, and the electrode slurry 44 is applied from the other surface 40b side of the porous support body 40. The back surface lb of the solid electrolyte 1 is infiltrated, and the surface la of the solid electrolyte 1 is coated with the electrode slurry 43, which is baked to obtain electrodes 3 and 4 on both the front and back surfaces of the solid electrolyte 1. This manufacturing direction will be further described. The support 40 is formed as a porous material and can be made of, for example, aluminum oxide as described above. The reason for masking the one surface 40a of the support 40 is that when the average pore size of the support 40 is increased (for example, when the average pore size is 30 am), the electrolyte slurry 41 is directly applied on the one surface 40a. Then, there is also a force that the electrolyte slurry 41 enters (permeates) into the support 40. However, this can be prevented by applying the masking. In addition, when the average pore diameter force S of the support 40 is small (for example, 3 m or less), this masking is unnecessary.

In order to constitute the solid electrolyte 1, the electrolyte slurry 41 is obtained by adding a fine molten material (pellet) and a binder as a pore former to an electrolyte powder (electrolyte particles) and adjusting the viscosity with a solvent. The electrode slurries 43 and 44 for constituting the electrodes 3 and 4 include a metal powder (silver particles) constituting the electrode, for example, silver powder, and a micro molten material (pellet) and a binder as a pore former. The viscosity was adjusted with a solvent. In order to make the electrodes 3 and 4 contain the same material as the solid electrolyte 1, add electrolyte powder (electrolyte particles) to the electrode slurries 43 and 44! /.

[0088] The electrolyte slurry 41 is coated on the one surface 40a side of the support 40 and baked to obtain the solid electrolyte 1 on the support 40. In the case of a zirconium oxide electrolyte, the firing temperature is set to 1300 ° C to 1400 ° C. Thereby, the porous solid electrolyte 1 can be obtained on the support 40. In addition, the method for producing the porous support 40 is also obtained by adding a finely melted material (pellet) and a binder to the metal powder constituting the support 40, and firing the material whose viscosity is adjusted with a solvent. It is done.

Then, an electrode slurry 44 for forming the second electrode 4 is applied to the other surface 40b side of the porous support 40, and the electrode slurry 44 is infiltrated to the back surface lb of the solid electrolyte 1. The Further, the electrode slurry 43 for forming the first electrode 3 is covered on the surface la of the solid electrolyte 1. Then, this is fired to obtain electrodes 3 and 4 on both the front and back surfaces of solid electrolyte 1. When the electrodes 3 and 4 are made of silver, the firing temperature is set to 800 ° C to 900 ° C. Since this manufacturing method is a manufacturing method in which the solid electrolyte 1 is first fired and then the first and second electrodes 3 and 4 are fired, the melting points of the materials of the first and second electrodes 3 and 4 are solid. It is effective when it is lower than the firing temperature of the electrolyte 1. That is, the firing temperature of the solid electrolyte 1 is 1400 ° C, whereas the first is made of silver. In the case where the melting point of the second electrodes 3 and 4 is 930 ° C, if the solid electrolyte 1 and the electrodes 3 and 4 are simultaneously fired at 1400 ° C, the silver constituting the electrodes 3 and 4 aggregates. However, this production method can prevent silver from aggregating. Then, it is possible to obtain a porous and integrated purification structure 30.

[0090] Further, in order to provide the adsorbent 5 as the adsorbent 5 on the second electrode 4 side of the purification structure 30, the electrode slurry 44 for the second electrode 4 may contain norlium (barium oxide). That's fine. In addition, in the purification structure 30 that does not have the support 40, in order to provide normodium as an adsorbent on the second electrode 4 side, an aqueous barium acetate solution is provided on the sintered second electrode 4 May be applied by spraying or brushing and penetrating.

[0091] According to the purification apparatus of each of the embodiments described above, the diesel particulates in the exhaust gas also contain hydride carbon (HC), and this hydride carbon is water by supplying oxygen from the solid electrolyte 1. And the ability to oxidize to carbon dioxide (CmHn + (m + n / 4) 0 → mCO + n / 2 HO).

Furthermore, the purification device, the purification method, and the purification system according to the present invention can be applied not only to purification of exhaust gas discharged from a diesel engine but also to a wide range such as chemical synthesis and combustion systems. Further, the present invention is not limited to the illustrated form, and other forms may be used within the scope of the present invention. Besides the solid electrolyte 1 having a panel shape, a cylindrical shape or a corrugated shape may be used depending on the part to be installed. Etc.

[0092] The purification devices shown in Figs. 1 to 4, 10, and 18 are not only allowed to function alone, but also added to the conventionally known nitrogen oxide purification devices and particulate purification devices. Can also be granted. In other words, since the purification system of the present invention has a simple structure and can make the apparatus compact, the conventional apparatus can be added as an auxiliary oxidation system when diesel particulates are insufficiently oxidized.

Furthermore, in the purification apparatus shown in FIGS. 1 to 4, the charging device that serves as an electrostatic precipitator by corona discharge or the like is provided, and diesel particulates contained in the exhaust gas are efficiently deposited on the deposition surface 12 of the solid electrolyte 1. You may make it deposit well.

[0093] As described above, according to the present invention, it is possible to efficiently perform the oxidation of diesel fine particles, the reduction of nitrogen oxides, and the simultaneous treatment thereof by the injection of minute energy. It is possible to achieve exhaust gas purification at a high level. Therefore, if this purification device, purification method, and exhaust gas purification system are applied to the purification of exhaust gas from diesel engines, it is possible to purify exhaust gas while maintaining high thermal efficiency of diesel engines, which may be useful for environmental protection. it can.

Each of the above-described purification device, purification method, and exhaust gas purification system has been described as purifying exhaust gas from which diesel engine power is also exhausted. However, exhaust gas is not limited to that exhausted from diesel engine power. The present invention can also be applied to a gasoline engine (direct-injection gasoline engine), a boiler and an industrial furnace that have also been discharged.

Claims

The scope of the claims

[1] A solid electrolyte having ionic conductivity and capable of supplying oxygen ions to one side, and a first electrode and a second electrode provided on one side and the other side of the solid electrolyte, respectively. It has a purification structure,

The purification structure can collect the fine particles on the first electrode side by passing exhaust gas containing unburned fine particles discharged from the combustor from the first electrode side to the second electrode side. It is porous, and the first electrode side is an oxidation part that oxidizes the collected fine particles with oxygen ions given to the first electrode side by the solid electrolyte,

The purification apparatus according to claim 1, further comprising a support for increasing the mechanical strength of the purification structure.

[2] The support is provided in a state of being laminated with the first electrode or the second electrode, and the support has a network structure or a porous structure through which the exhaust gas can pass. 1. The purification device according to 1.

[3] The purification device according to claim 1 or 2, wherein at least one of the first electrode and the second electrode contains the same material as the solid electrolyte.

4. The purification device according to claim 1 or 2, wherein the first electrode contains silver.

[5] A porous solid electrolyte having ionic conductivity and capable of giving oxygen ions to one side, and a first electrode and a second electrode provided on one side and the other side of the solid electrolyte, respectively

A purification method using a purification structure having a support for increasing mechanical strength,

By passing an exhaust gas containing unburned fine particles from the one surface side to the other surface side of the solid electrolyte made of a porous material, the fine particles are collected on the one surface side, and the collected fine particles are collected by the solid electrolyte. A purification method comprising oxidizing with the oxygen ions given to the one surface side.

[6] Combustor power Emission provided with an exhaust passage for passing exhaust gas containing unburned particulates and nitrogen oxides, and an exhaust gas purification device provided in a part of the exhaust passage A gas purification system, The exhaust gas purifying device has a solid electrolyte that has ionic conductivity and can provide oxygen ions on one side, a first electrode and a second electrode provided on one side and the other side of the solid electrolyte, respectively. A purification structure having

This purification structure is porous so that the fine particles can be collected on the first electrode side by passing the exhaust gas from the exhaust passage from the first electrode side to the second electrode side. The first electrode side is an oxidation part that oxidizes the collected fine particles by oxygen ions given to the first electrode side by the solid electrolyte, and the second electrode side Is a reducing section that reduces nitrogen oxides contained in the exhaust gas that has passed through the purification structure,

The exhaust gas purification system, wherein the purification structure further includes a support for increasing the mechanical strength of the purification structure.

A solid electrolyte that has ionic conductivity and can provide oxygen ions on one side, and the first and second electrodes provided on one side and the other side of the solid electrolyte, respectively, increase mechanical strength. A purification structure having a porous support for forming a solid electrolyte on the support by coating an electrolyte slurry on one side of the support and firing the slurry. Then, the electrode slurry is infiltrated from the other surface side of the porous support to the back surface of the solid electrolyte, and the electrode slurry is coated on the surface of the solid electrolyte, and this is fired to form both surfaces of the solid electrolyte. A method for producing a purification structure, comprising obtaining an electrode.